An excellent article on the history of advertising written by Randall Rothenberg for Ad Age. Certainly an article that new people in the business should read and study.

He finishes the article with this:

But as we near the end of the broadcasting era, at the twilight of the advertising century, this much is now clear: In the spark of creativity lies the future of business.

This is a fundamental truth, regardless of changing technology and the advance of metrics. Though, Bill Bernbach in the 1960's said it best when challenged with the silly idea that advertising is science:

Advertising is fundamentally persuasion and persuasion happens to be not a science, but an art.

He also said:

However much we would like advertising to be a science-because life would be simpler that way-the fact is that it is not. It is a subtle, ever-changing art, defying formulaization, flowering on freshness and withering on imitation; where what was effective one day, for that very reason, will not be effective the next, because it has lost the maximum impact of originality.

The more things change, the more they stay the same.